I was running much the same set up as you BUT with the CV carb...

46 Idle & 185 Main worked real well 4 me..

Whats jets are you running now ? CV sizes are diff' than a 42 Mik'
You should be looking at around a 20 to 25 Pilot, and a 160 to 165 main.
 

Tuning guide here: www.mikuni.com/pdf/hsr_tuningmanual_021003.pdf

I'm running 20 pilot and a 170 main on warm 95. I tuned it with a Wideband AFR meter.
What rev range do you think it's lean ?

I guess you've tried richening the Idle mixture screw ? You could try 1 richer on the Pilot.
I find it all guess work, unless you know the actual AFR's.